Check valve including means to permit selective back flow

Abstract

A preferred embodiment of FIGS. 1-3 includes a check valve (10) with a pair of semicircular check valve members (34, 36) normally permitting fluid flow in one direction and blocking fluid flow in an opposite direction. Semicircular valve member (36) is releasably locked in an open position to permit a back flow upon manual rotation of handle (46) after manual gripping of knurled knob (84) and withdrawal of a locking pin (82) from a receiving opening (96). A safety lever (98) is pivoted out of a covering relation to knob (84) before knob (84) is gripped and prevents rotation of shaft (38) unless lever (98) is manually pivoted out of covering relation with knob (84). Another embodiment shown in FIG. 4 permits selective opening of a semicircular plate valve member (34A or 36A) to a releasably locked open position. Manual rotation of handle (46A) in one direction effects movement of semicircular valve member (36A) to an open position. Separate manual movement of handle (46B) in an opposite direction effects rotation of plate valve member (34A) to an open position. Another embodiment shown in FIGS. 5 and 6 provides a planetary gear arrangement which is effective to rotate the check valve members simultaneously to an open position. Rotation of handle (46C) effects rotation of shaft (38C) in one direction for opening of one of the semicircular valve members and rotation of sleeve or shaft (42C) in an opposite direction effects rotation of the other check valve member to an open position.

We claim: 
     
       1. A check valve for normally permitting fluid flow in one direction and for normally blocking fluid flow in an opposite direction; said check valve comprising: a valve body having a flow passage therethrough;   a plate valve member pivotally mounted within said valve body responsive to fluid pressure from one direction for normal pivotal movement to an open position permitting fluid flow, and responsive to fluid pressure from an opposite direction for normal pivotal movement to a closed position blocking fluid flow;   a shaft operatively connected to said plate valve member;   a manually operated handle connected to said shaft for manual rotation of said plate valve member;   a manually releasable locking member for releasably locking said shaft and plate valve member at a predetermined open position of said plate valve member; and   means to restrict manual access to said releasable locking member to prevent inadvertent actuation of said manually releasable locking member.   
     
     
       2. A check valve as set forth in claim 1 wherein said releasable locking member comprises a locking pin and a spring urging the locking pin within a recess in said body for releasably locking said shaft. 
     
     
       3. A check valve as set forth in claim 1 wherein a cover is positioned over said releasable locking member to prevent manual access to said locking member for actuation thereof. 
     
     
       4. A check valve as set forth in claim 3 wherein said cover is mounted for pivotal movement between a normal first position in covering relation to said locking member to prevent access and a second position removed from covering relation to permit access to said locking member. 
     
     
       5. A check valve as set forth in claim 4 wherein a separate locking member is connected to said cover to releasably lock said cover in covering relation to said locking member to prevent access to said first mentioned releasable locking member. 
     
     
       6. A check valve as set forth in claim 1 wherein resilient means continuously forces said plate valve member to a closed position; and said handle moves said plate valve member to an open position against the force of said resilient means. 
     
     
       7. A check valve as set forth in claim 6 wherein said plate valve member is generally semicircular. 
     
     
       8. A check valve as set forth in claim 1 wherein said manually releasable locking member comprises a manually actuated retaining pin received within an aligned opening at the normal operating position of said plate valve member and within another aligned opening positioned at about ninety (90) degrees to said first mentioned aligned opening; and means permit pivotal movement of said plate valve member during normal operation between said open position and said closed position when said pin is in said first mentioned aligned opening.   
     
     
       9. A check valve as set forth in claim 8 wherein said manually actuated retaining pin is movable manually between an inward projected position at the open position for retaining said plate valve member in a locked position, and an outward retracted position to permit manual rotation of said plate valve member. 
     
     
       10. A check valve as set forth in claim 9 wherein a manually actuated safety member is movable manually between a position blocking manual operation of said retaining pin and a position permitting manual operation of said pin, said safety member requiring manual movement of said safety member to said position permitting manual operation before manual actuation of said retaining pin. 
     
     
       11. In a check valve for normally permitting fluid flow in one direction and for normally blocking fluid flow in an opposite direction; said check valve having a valve body having a flow passage therethrough and a pair of semicircular plate valve members pivotally mounted within said valve body responsive to fluid pressure from one direction for normal pivotal movement to an open position permitting fluid flow, and responsive to fluid pressure from an opposite direction for normal pivotal movement to a closed position blocking fluid flow; improved valve operating means comprising: a shaft operatively connected to at least one plate valve member;   a manually operated handle connected to said shaft for manual rotation of said one plate valve member;   a manually releasable locking member for releasably locking said shaft and said one plate valve member at a predetermined open position of said one plate valve member; and   means to block manual access to said releasable locking member to prevent inadvertent actuation of said manually releasable locking member.   
     
     
       12. In a check valve as set forth in claim 11 wherein resilient means continuously forces said plate valve members to a closed position for normal operation; and said handle is effective to move said one plate valve member to said open back flow position against the force of said resilient means. 
     
     
       13. In a check valve as set forth in claim 11 wherein said handle is operatively connected to both of said semicircular plate valve members for manual pivotal movement of said plate valve members to a releasably locked open position to permit fluid flow in said opposite direction through both of said plate valve members. 
     
     
       14. In a check valve as set forth in claim 13 wherein a separate shaft is operatively connected to each of said semicircular plate valve members for movement of said plate valve members to open position. 
     
     
       15. In a check valve as set forth in claim 13 wherein said valve operating means includes a single manually operated shaft; and a gear structure is arranged between said shaft and said semicircular plate valve members for simultaneous movement of said semicircular plate valve members to an open position upon rotation of said manually operated shaft. 
     
     
       16. In a check valve as set forth in claim 11 wherein said valve operating means includes a manually operated pin received within an aligned opening at the normal operating position of said one plate valve member and within another aligned opening positioned at about ninety (90) degrees to said first mentioned aligned opening; and means permit pivotal movement of said one plate valve member during normal operation between said open position and said closed position when said pin in said first mentioned aligned opening.   
     
     
       17. In a check valve as set forth in claim 11 wherein said releasable locking means comprises a manually actuated retaining pin movable manually between an inward projected position at the open position for retaining said one plate valve member in a locked position and an outward retracted position to permit manual rotation of said one plate valve member. 
     
     
       18. A check valve as set forth in claim 17 wherein a manually actuated safety member is movable manually between a position blocking manual operation of said pin and a position permitting manual operation of said pin, said safety member requiring manual movement of said safety member to said position permitting manual operation before manual actuation of said pin.